(a) Field of the Invention
The present invention relates to a high carbon steel sheet. More particularly, the present invention relates to a fine spheroidized steel sheet having a fine pearlite structure and an excellent heat treatment characteristic, and a method for manufacturing the same.
(b) Description of the Related Art
A high carbon steel sheet is a graphite steel sheet that has 0.3 wt % or more of carbon, and has a crystal structure with a pearlite crystal phase. The high carbon steel sheet has a high strength and a high hardness after a final process. As described above, since the high carbon steel sheet has the high strength and the high hardness, the high carbon steel sheet is used for tool steel or steel for machine structural use requiring the high strength and the high hardness.
As examples of the high carbon steel sheet used as the tool steel, there is JS-SK85 steel classified according to Japanese Industrial Standard. The JS-SK85 steel is used for parts for vehicles, needles for removers, razor blades, or stationary knives.
The high carbon steel sheet is generally manufactured as an intermediate product such as a hot rolled steel sheet by a continuous hot rolling process of a slab. The hot rolled steel sheet is manufactured by rolling the slab heated for hot rolling through roughing rolling and finish rolling in a predetermined thickness, cooling to an appropriate temperature in a run-out table (ROT), and winding using a scroll type of coil.
The hot rolled steel sheet is manufactured into a cold rolled steel sheet by using cold rolling after pickling and spheroidizing annealing processes. The cold rolled steel sheet having a desired thickness is manufactured by sequentially repeating an annealing process and a cold rolling process.
The cold rolled steel sheet is processed into a desired product through processes such as blanking or burring, and then, is processed into a final product through a QT (quenching and tempering) heat treatment.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.